long term immunogenicity study of engerix-b vaccine in 10 year old children and the effect of booster injections

Conditions: Hepatitis B; Vaccination

Summary: hepatitis b immunization has been offered to all grade 4 students (age 9-10) in the province of quebec, using engerix-b at a dose of 10 mkg. the peak incidence of hepatitis b occurs between age 15 and 35; the proportion of vaccinated children who will still be protected at this age is currently unknown. this study is designed to determine: * persistence of immunity until age 25 * persistence of immunological memory as demonstrated by an anamnestic response following a booster dose * the effect of a booster dose on immunogenicity at either 5, 10 or 15 years after the primary vaccination course (at age (15, 20 or 25).

three doses of engerix-b vaccine (10 mkg) were administered according to 0, 1, 6 month schedule to 1126 9-10 year-old children. the primary objective of the study is to evaluate the persistence of antibodies to engerix-b in all subjects at age 25 and to compare the levels obtained in those given a booster injection at age 15 or 20 with those receiving no booster injection. secondary objectives * to determine the antibody levels obtained following primary vaccination and the proportion of children who seroconvert * to determine the antibody levels of one third of subjects at age 15, 5 years after primary vaccination (group a) * to determine the effect on antibody levels of a booster injection at age 15 years given to one third of the subjects (group a) * to determine the antibody levels of subjects in groups a and b at age 20, 5 years after booster (group a), 10 years after primary vaccination (group b) * to determine the effect on antibody levels of a booster injection at age 20 years given to one third of the subjects (group b) * to determine the effect on antibody levels of a booster injection at age 25 years given to one third of the subjects (group c) * to determine the antibody levels of subjects in group a and group b one year after their 5 or 10 year booster * to evaluate safety

Eligibility criteria:
inclusion criteria: * previously completed the 1995 to 1996 hepatitis b vaccination program vaccinations (primary study) to the best of his/her knowledge and already enrolled and followed in the long term study * must be hbc negative * required standard interval between last dose of primary immunization and booster vaccination * written informed consent obtained from the subject * free of obvious health problems as established by medical history and clinical examination before entering into the study * previously completed routine childhood vaccination to the best of his/her knowledge * if the subject is female, and the potential of pregnancy exists, it must be asked prior to immunization by the study nurse. according to the protocol d'immunisation du québec, engerix-b is not contra-indicated during pregnancy. however, if a participant thinks she could be pregnant (sexually active and no oral contraception or intra uterine device), a pregnancy test will be carried out. in case of pregnancy, the booster vaccination will be performed after delivery. exclusion criteria: - not applicable

Keywords: hepatitis b vaccination engerix-b immunogenicity long-term immunity booster dose safety